car stereo making funny noise

Whenever I turn my car on and off or for that matter my radio there is really loud feedback. It sounds like it is going to break the subwoofer since only bass is coming out, LOUD. Can someone help me with my headaches?

what does the feedback sound like. does it change as the engine revs? is it a new problem, or has it always happened? need a little more details, it could be numberous things. power and signal wires in close proximity can cause engine feedback, an amp not grounded properly can cause feedback...

As the previous message indicated, it is entirely possible this is simply a ground issue. While other possibilities exist, the correct action is to make sure your head unit is grounded with your amplifier. (If the amp is in the trunk that means bringing the ground wire to the head unit.) Ideally, you want all of the grounds in your audio to be of the same impendence. So if your head unit is on the same ground as your windshield wipers, A/C, etc., that obviously has a different value than an amp grounded directly to your trunk. This may or may not be the problem you identified, but it is the first step towards making your system sound cleaner.